A new type of X-ray sources was invented in Sweden. In these sources the anode hit by the electrons is a very fast (about 50 m/s) jet of liquid metal e.g. tin or gallium or nitrogen or methanol. The jet is produced by pressing the liquid under high pressure through a nozzle. The diameter of the jet is in the range of only 15 µm and so the source point diameter of the source is in the same range. When the jet is hit by the accelerated electrons, it evaporates. So the power per square centimetre can be much higher (about 1 MW/cm²) compared to X-ray tubes with standing or rotating anodes.